The invention relates to a container with at least one vacuum chamber with an access opening, especially to a beverage container with a self-cooling device having a vacuum chamber, such as a beer barrel or the like, the access opening of which is closed off by a closing mechanism after the vacuum is produced.
A self-cooling beer barrel is known, for example, from the EP 1 054 222. Such a beer barrel has several chambers, namely, on the one hand, a bubble for holding the beverage, a chamber, which surrounds the bubble and forms an evaporator space, and a third chamber, which surrounds these two chambers and forms an absorber space, in which an absorbent, especially a zeolite granulate, is disposed. The evaporator space and the absorber space are divided from one another by a partition, in which a valve device is disposed. Water is used as evaporator material. In order to be able to cool the beverage, the absorber space, to begin with, is evacuated with the help of a heating step and dried. The zeolite granulate, contained in the absorber space, is brought to ambient temperature once again before the beverage is filled into the bubble or while it is already in the bubble. If now the valve device is opened before the barrel is tapped and, with that, the evacuated absorber space is connected with the evaporator space, water vapor flows from the evaporator space into the absorber space. An evaporation process takes place, which requires heat, which, in turn, is withdrawn from the beverage, so that the latter is cooled. This evaporation and absorption take place until the crystalline zeolite is saturated with water or the valve is closed and the transfer of water vapor is interrupted. In order to start the cooling process, the valve in the partition can be actuated from outside by a suitable mechanism with an opening lever or the like.
Such a beverage container is a reusable container, that is, the possibility exists of regenerating the self-cooling device and, after the bubble is filled, of operating the barrel once again. The key feature for the functioning of the self-cooling device is the vacuum in the vacuum chamber of the self-cooling device. This vacuum must be maintained for a long time, in order to be able to ensure the reversible evaporation operation and, by these means, the repeated usability of the container.
In the case of a container, known from the state-of-the-art described above, the vacuum chamber of the self-cooling device is closed off after the final evacuation using suitable means, usually a screw with a washer that is screwed into a threaded borehole. As a further precaution, a cover is welded tightly over the closing screw. However, these means do not necessarily ensure that the barrel actually is closed tightly and does not have a leak, because there is no possibility of measuring the vacuum produced after the access opening of the container has been closed off.
However, this is a problem, which exists not only for the container described above in the form of a self-cooling beverage barrel, but also in the case of other one-chamber or multichamber vacuum containers, which are closed off after the vacuum is produced.